Where is the water going?

Every 3 days or so I have to add water to my radiator. There are no leaks, no steam and no smoke. My oil is not milky and my motor never gets over 200 when running, normally runs between 160 and 180, which is good for a 350. I cant figure out where the water is going any ideas?

Try a new rad cap. If its not holding pressure, the water can escape as steam, even at lower operating temperatures.

Thanks that's what I was thinking but not sure.

This might be an over kill but this has happened to me on a reconditioned 350 i done .
Recoed the heads but they were never pressure tested and one of the ports had a pin hole which was not picked up with a crack test. It leaked very little and as time went on like 6 months it filled the cylinder with water.
Check your spark plugs, This is a long shot but it has happened to me.

I agree it could be getting in the cylinders. I have had a small crack on some old camel hump heads right in the intake valve seat. The engine would run fine but did loose water. I too ended up filling a cylinder with water. A sign that water is getting in the cylinder while running is if you pull your plugs the one that has water getting in there will look brand new. When I pulled the heads I found the cylinder the water was getting in had a very clean piston and the combustion chamber in the head along with valves were very clean.
Like said above I hope it's not your problem and of course check the simple things first.